Frozen Account Operations Remediation

Overview

Related Detector: Frozen Account Operations

Token operations on frozen accounts fail at the SPL Token runtime level. Adding explicit frozen state checks improves error messages and prevents unexpected control flow.

Recommended Fix

Before (Vulnerable)

// No frozen check -- SPL Token rejects with generic error
let ix = spl_token::instruction::transfer(...)?;
invoke(&ix, accounts)?;

After (Fixed)

// Explicit frozen check with clear error message
let token_data = Account::unpack(&source.data.borrow())?;
if token_data.state == AccountState::Frozen {
    msg!("Token account is frozen, cannot transfer");
    return Err(ProgramError::Custom(ErrorCode::AccountFrozen as u32));
}

let ix = spl_token::instruction::transfer(...)?;
invoke(&ix, accounts)?;

Alternative Mitigations

1. Anchor constraint

#[account(
    mut,
    constraint = token_account.state != AccountState::Frozen @ ErrorCode::AccountFrozen
)]
pub token_account: Account<'info, TokenAccount>,

2. Helper function

Create a reusable validation function:

fn require_not_frozen(account: &AccountInfo) -> ProgramResult {
    let data = Account::unpack(&account.data.borrow())?;
    if data.state == AccountState::Frozen {
        return Err(ProgramError::Custom(ErrorCode::AccountFrozen as u32));
    }
    Ok(())
}

Common Mistakes

Mistake 1: Only checking source, not destination

// INCOMPLETE: destination may also be frozen
require_not_frozen(source)?;
// Missing: require_not_frozen(destination)?;

References

• SPL Token AccountState
• CWE-754: Improper Check for Unusual Conditions